1. Field of the Invention
The present invention relates to an optical element, an optical module, an optical connector, and an optical module manufacturing method. In particular, the present invention relates to an optical element, an optical module, an optical connector, and an optical module manufacturing method that are suitable for controlling an amount of outgoing light when incident light is outputted.
2. Description of the Related Art
Conventionally, a polarizer, a diffraction grating, and the like are known as an optical element having a function for controlling an amount of outgoing light to a desired amount of light, when incident light is outputted by transmission or the like.
Regarding an optical element such as this, the present applicants and others have proposed an invention that is an optical module used in optical communication, in Japanese Patent Application No. 2003-84965. In the optical module, a diffraction grating is disposed between an optical fiber and a photoelectric conversion element. A holder, a lens, and the diffraction grating are integrally formed from resin material.
Conventional technologies, such as those described in Patent Literatures 1 and 2, have been disclosed regarding this type of optical element.
Patent Literatures 1 and 2 disclose adjustment of an amount of light to be used. The adjustment is made by a component, such as a polarizer, being rotated.
Other than those described in Patent Literatures 1 and 2, there is a technology in which laser outputted from a transmitter optical sub-assembly (TOSA) of an optical front-end (OFE), used in fiber optic communication, is adjusted. Specifically, in the technology, filters and materials having various transmittances are prepared, and transmittance of a laser beam is adjusted. As a result, the intensity of the laser being incident on an optical fiber is weakened. In a technology such as this, for example, the light incident on an optical element can be weakened and outputted, for example, every one to five percent.
[Patent Literature 1] Japanese Patent Unexamined Publication No. Heisei 5-207384
[Patent Literature 2] Japanese Patent Unexamined Publication No. Heisei 4-100012
However, the conventional technologies disclosed in Patent Literatures 1 and 2 have problems such as those described below.
In other words, a polarizing plate stop device described in Patent Literature 1 uses two polarizing plates and adjusts the amount of light by making the polarization directions of the two polarizing plates intersect with each other. As a result, costs increase because two polarizing plates are used. In addition, the assembly process becomes complex because the amount of light is required to be adjusted for each of the two polarizing plates.
An optical module described in Patent Literature 2 provides light output that is adjusted to a desired level by a deflector being rotated around an optical axis. Stability against disturbances caused by temperature fluctuations and the like can be achieved. However, there is no indicator regarding the amount by which the deflector is rotated. As a result, the light output cannot be adjusted quickly during the manufacturing process, and assembly efficiency is poor.
Furthermore, even when the amount of light is adjusted using the filter and the like described above, the problem of increased costs caused by the filter and the like being required cannot be avoided.